Variable valve lift mechanism for engine and arrangement of oil control valve

ABSTRACT

An engine has a cylinder block mounted on a crankcase and a cylinder head mounted on the cylinder block. The cylinder head has one side forming an intake port and an intake valve and another side forming an exhaust port and an exhaust valve. A camshaft includes an intake cam assembly and an the exhaust cam assembly, which respectively drive an intake valve driving member and an exhaust valve driving member. The intake cam assembly includes a first intake cam and a second intake cam. The intake valve driving member includes a low lift driving member corresponding to the first intake cam and a high lift driving member corresponding to the second intake cam. The low lift driving member and the high lift driving member form a hydraulic cylinder, which receives therein hydraulically operable pistons.

TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to a variable valve liftmechanism for engine and an arrangement of oil control valve, and moreparticularly to a structure that prevent interference of the oil controlvalve with maintenance of other parts and realizes movement of valvedriving member of engine for high and low lifts in order to miniaturizethe oil pump and reduce engine power loss.

DESCRIPTION OF THE PRIOR ART

Oil passage arrangement for a conventional variable valve lift mechanismof an engine 1 is shown in FIG. 1, wherein an electromagnet valve 2 ismounted on a cylinder head 11. Oil received at hydraulic oil entrance isguided by a pipe 21 to supply external pressure to the electromagneticvalve 2, and then the electromagnetic valve 2 introduces the lubricationoil into oil passages inside the cylinder head 11 to allow the hydraulicpressure to be applied to drive variable lift mechanism of each cylinderso as to realize switching of intake and exhaust valves in response todifferent rotational speeds of the engine 1.

The arrangement of the electromagnetic valve 2 and the oil pipe 21 ofthe conventional engine 1 are effective in realizing switching of intakeand exhaust valves in response to different rotational speeds of theengine 1. However, the electromagnetic valve 2 is mounted to thecylinder head 11 by bolts 22. The assembling is complicated. Further,the oil pipe 21 connected to the electromagnetic valve 2 is susceptibleto oil leakage and due to exposure outside the engine 1, it issusceptible to damage due to high temperature of the engine 1. Further,since the electromagnetic valve 2 is arranged above the cylinder head11, when the engine 1 swings, the electromagnetic valve 2 may easily getinterfering with an upper side part, such as a storage box.

In view of the above discussed problems of the conventional arrangementof oil passage for variable valve lift mechanism, the present inventionaims to provide an oil control valve that simplifies the assembling ofengine and allows of easy arrangement of lubrication oil passage and astructure to miniaturize the oil pump and reduce power loss of engine.

SUMMARY OF THE INVENTION

The technical solution adopted in the present invention is to provide avariable valve lift mechanism and arrangement of control valve. Theengine comprises a cylinder block mounted on a crankcase and a cylinderhead mounted on the cylinder block. The cylinder head has one sideforming an intake port and an intake valve and another side forming anexhaust port and an exhaust valve. A throttle valve communicates throughan intake tube with the intake port. The intake valve and the exhaustvalve are provided therebetween with a camshaft base. The camshaft basecomprises a camshaft, and the camshaft comprises an intake cam assemblyand an exhaust cam assembly, which respectively drive an intake valvedriving member and an exhaust valve driving member. The intake camassembly includes a first intake cam and a second intake cam. The intakevalve driving member comprises a low lift driving member correspondingto the first intake cam and a high lift driving member corresponding tothe second intake cam. The low lift driving member and the high liftdriving member form a hydraulic cylinder, which receives thereinhydraulically operable pistons. The oil control valve comprises adriving oil passage communicating the hydraulic cylinder. The high liftdriving member of the intake valve driving member is closer to the oilcontrol valve than the low lift driving member. The path of the drivingoil passage of the oil control valve and the high lift driving member isshorter than the path of the driving oil passage that the oil controlvalve drives the low lift driving member.

Another technical solution adopted in the present invention is toprovide a variable valve lift mechanism for engine and arrangement ofoil control valve, wherein the oil control valve seat is integrallyformed on a surface of an intake port side of the cylinder head to besubstantially perpendicular to an intake port and is located on an outerwall of a timing chain chamber. The oil control valve seat is set lowerthan the greatest height of the throttle valve. Further, the oil controlvalve seat is substantially in line with a timing chain tensioner and islocated on the same side as the timing chain and is substantiallyparallel to the intake tube. The oil control valve seat forms an openingthat is faces toward the cylinder block to receive the oil control valveto be mounted thereto. The oil control valve is mounted to the oilcontrol valve seat in such a way to face from the cylinder block towardthe cylinder head. In other words, a wire outlet joint end of the oilcontrol valve faces toward the cylinder block in order to eliminateinterference of the oil control valve with maintenance of other parts.

The foregoing objectives and summary provide only a brief introductionto the present invention. To fully appreciate these and other objects ofthe present invention as well as the invention itself, all of which willbecome apparent to those skilled in the art, the following detaileddescription of the invention and the claims should be read inconjunction with the accompanying drawings. Throughout the specificationand drawings identical reference numerals refer to identical or similarparts.

Many other advantages and features of the present invention will becomemanifest to those versed in the art upon making reference to thedetailed description and the accompanying sheets of drawings in which apreferred structural embodiment incorporating the principles of thepresent invention is shown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a conventional cylinder head.

FIG. 2 is a cross-sectional view of an engine according to the presentinvention.

FIG. 3 is a perspective view schematically showing oil route accordingto the present invention.

FIG. 3A is an enlarged sectional view illustrating the way how thethrottle arrangement is mounted inside the crankshaft oil supplypassage;

FIG. 3B is an enlarged sectional view illustrating the way how thethrottle arrangement is mounted inside the valve driving member oilsupply passage;

FIG. 4 is a perspective view of an engine according to the presentinvention.

FIG. 5 is a schematic view of a variable valve lift mechanism accordingto the present invention.

FIGS. 6 and 7 are schematic views illustrating the operation of thevariable valve lift mechanism according to the present invention.

FIG. 8 is a perspective view illustrating an oil control valve accordingto another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following descriptions are exemplary embodiments only, and are notintended to limit the scope, applicability or configuration of theinvention in any way. Rather, the following description provides aconvenient illustration for implementing exemplary embodiments of theinvention. Various changes to the described embodiments may be made inthe function and arrangement of the elements described without departingfrom the scope of the invention as set forth in the appended claims.

The present invention provides an engine 3, which is arranged, in asubstantially horizontal manner, on a scooter as a rocker engine 3.First of all, reference is made to FIG. 2. The engine 3 according to thepresent invention comprises a crankcase 31, a cylinder block 32 mountedon the crankcase 31, a cylinder head 33 mounted on the cylinder block32, and a cylinder head cover 34.

The crankcase 31 receives therein a crankshaft 310. Referring to FIGS.3, 3A and 3B the crankcase 31 comprises therein an oil pump 311. The oilpump 311 pumps oil into a primary oil supply passage 312. The primaryoil supply passage 312 extends from the crankcase 31 through thecylinder block 32 to the oil control valve 4 mounted to the cylinderhead 33. The primary oil supply passage 312 has an end forming acrankshaft oil supply passage 312 a toward the crankcase 31. Thecrankshaft oil supply passage 312 a has an end forming a throttlearrangement 312 a′ that supplies oil to a crankshaft bearing. Thethrottle arrangement 312 a′ comprises a nozzle. The throttle arrangement312 a′ functions to regulate the internal pressure of the primary oilsupply passage 312 and the ejected amount of oil and also functions todirect the oil to eject to a predetermined direction.

The cylinder block 32 is coupled to the crankcase 31 and allows a timingchain 5 to extend therethrough. The cylinder block 32 comprises a timingchain tensioner 51 arranged at the intake port 331 side of the cylinderhead 33, as shown in FIGS. 1 and 4. Further, the timing chain tensioner51 is arranged to be substantially in line with the oil control valve 4.Since the timing chain chamber 330 provides a large amount of internalspace, it is possible to prevent heat accumulation occurring at thelocation where an oil control valve seat 339 is mounted.

The cylinder head 33 comprises an intake port 331 and an intake valve332 arranged at the intake side and an exhaust port 333 and an exhaustvalve 334 arranged at the exhaust side. A throttle valve 6 communicatesthrough an intake tube 321 with the intake port 331 of the intake side.Referring to FIGS. 3, 3A, 3B, 4, 5, and 6, the cylinder head 33comprises an integrally formed cast camshaft base 335 between the intakevalve 332 and the exhaust valve 334. The camshaft base 335 supports arotatable camshaft 336. The camshaft 336 comprises an intake camassembly 3361 and an exhaust cam assembly 3362 mounted thereon. Theintake cam assembly 3361 includes a first intake cam 3361 a (which is alow lift cam) and a second intake cam 3361 b (which is a high lift cam).The intake cam assembly 3361 and the exhaust cam assembly 3362 functionto push intake valve driving member 337 and exhaust valve driving member337′ of the intake valve 332 and the exhaust valve 334 during therotation of the camshaft 336. The intake valve driving member 337comprises a low lift driving member 3371 and a high lift driving member3372 of variable valve lift mechanism. The low lift driving member 3371and the high lift driving member 3372 are provided with a hydrauliccylinder 338. The hydraulic cylinder 338 receives therein a first piston3381 and a second piston that can be hydraulically moved. The oilcontrol valve 4 comprises a driving oil passage 3383 communicating thehydraulic cylinder 338. The driving oil passage 3383 includes a firstdriving oil passageway 3383 a and a second driving oil passageway, whichare respectively located at the ends of the low lift driving member 3371and the high lift driving member 3372 close to the hydraulic cylinder338. The oil control valve 4 functions to set the low lift drivingmember 3371 and the high lift driving member 3372 to move together or tomove individually. The driving oil passage 3383 extends from an oilcontrol valve seat 339 outside the cylinder head 33 through the cylinderhead 33 and the camshaft base 335 to the hydraulic cylinder 338 of thevalve driving member 337. Referring to FIGS. 3 and 6, the oil controlvalve seat 339 is integrally formed on a surface of the intake port 331of the cylinder head 33 to be substantially parallel to the intake tube321 and is located on an outer wall of the timing chain chamber 330. Theoil control valve seat 339 is set to be lower than the greatest heightof the throttle valve 6. Further, the oil control valve seat 339 issubstantially in line with the timing chain tensioner 51 and is locatedat the same side of the timing chain 5. The oil control valve seat 339forms an opening 3391, and opening 3391 is arranged to face the cylinderblock 32 to receive the oil control valve 4 to be mounted thereto. Theoil control valve 4 is mounted on the oil control valve seat 339 in sucha way to face from the cylinder block 32 toward the cylinder head 33. Inother words, a wire outlet joint end 4 a of the oil control valve 4faces toward the cylinder block 32. Further, the high lift drivingmember 3372 of the intake valve driving member 337 is arranged close tothe oil control valve 4. In other words, the high lift driving member3372 of the intake valve driving member 337 is more close to the oilcontrol valve 4 than the low lift driving member 3371. Namely, the pathof the driving oil passage 41H of the oil control valve 4 and the highlift driving member 3372 is shorter than the driving oil passage 41Lthat the oil control valve 4 drives the low lift driving member 3371.The oil control valve 4 is arranged in a substantially horizontal on thecylinder head 33 in order to eliminate the influence caused by gravityand thereby reducing the consumption of electrical power.

The cylinder head cover 34 is arranged on the cylinder head 33. Topractice the present invention, as shown in FIGS. 3, 3A and 3B, the oilpump 311 arranged in the crankcase 31 pumps oil to the primary oilsupply passage 312, which extends from the crankcase 31 through thecylinder block 32 to communicate the oil control valve 4 arranged in thecylinder head 33.

The oil control valve 4 comprises a plurality of oil channels 41 insidethe cylinder head 33, and the oil control valve 4 forms a plurality ofoil apertures 42. The number of the oil apertures 42 of the oil controlvalve 4 determines the number of oil channels inside the cylinder head33. Further, the end of the primary oil supply passage 312 toward thecrankcase 31 forms a crankshaft oil supply passage 41 a. Referring toFIGS. 3, 3A, 3B, 5, and 6, the primary oil supply passage 312 has an endtoward the cylinder head cover 34 and the end forming a valve drivingmember oil supply passage 41 b. The valve driving member oil supplypassage 41 b communicates the cylinder head 33. Through thecommunication of the valve driving member oil supply passage 41 b withthe cylinder head 33, oil is allowed to freely supply to the intakevalve driving member 337. The valve driving member oil supply passage 41b comprises a throttle arrangement 41 b′ inside the cylinder head cover34. The throttle arrangement 41 b′ comprises a nozzle. The throttlearrangement 41 b′ regulates the internal pressure of the primary oilsupply passage 312 and the amount of oil ejected, and to eject the oilin a predetermined direction in order to realize lubrication of thevalve driving member 337.

Referring to FIGS. 5 and 6, the oil control valve 4 supplies oil intothe first driving oil passageway 3383 a of the driving oil passage 3383of the cylinder head 33 to enter the hydraulic cylinder 338. A controlcenter ECU (not shown) of the engine 3 detects the moving condition ofthe vehicle and when it is determined that the valve needs to be openedin a low lift extent, the control center ECU of the engine 3 controlsthe oil control valve 4 to supply oil from the driving oil passage 3383into the hydraulic cylinder 338, as shown in FIG. 6, whereby hydraulicpressure causes the first piston 3381 and the second piston 3382 to movetoward the high lift driving member 3372 to have the second piston 3382located inside the high lift driving member 3372 and the first piston3381 located inside the low lift driving member 3371. Under thiscondition, the low lift driving member 3371 and the high lift drivingmember 3372 are allowed to individually rotate. Under this condition,due to engagement between the low lift driving member 3371 and the firstintake cam 3361 a (namely the low lift cam) of the camshaft 336, theintake valve of the engine 3 is set in a low lift opening condition. Asshown in FIG. 7, when the engine 3 is caused by a change of the movingcondition of the vehicle to have the intake vale changed to a high liftopening coition, the control center ECU of the engine 3 controls the oilcontrol valve 4 to supply oil from the second driving oil passageway3383 b of the driving oil passage 3383 into the hydraulic cylinder 338.The hydraulic pressure causes the first piston 3381 and the secondpiston 3382 to move toward the low lift driving member 3371 to have thefirst piston 3381 located in the low lift driving member 3371 and thesecond piston 3382 located at a position between the low lift drivingmember 3371 and the high lift driving member 3372. Under this condition,the low lift driving member 3371 and the high lift driving member 3372are movable in unison with each other. Due to the engagement between thehigh lift driving member 3372 and the second intake cam 3361 b (namelythe high lift cam) of the camshaft 3361, the low lift driving member3371 is moved by the high lift driving member 3372 to set the intakevalve 332 to a desired high lift opening condition by the lift of thesecond intake cam 3361 b (namely the high lift cam). This realizesvariation of valve lift of the engine 3.

Alternatively, in the practice of the oil control valve 4 according tothe present invention, as shown in FIG. 8, the oil control valve seat339 forms an opening 3391, which faces toward the cylinder head 33 toreceive the oil control valve 4 mounted thereto. The oil control valve 4is mounted on the oil control valve seat 339 in such a way to face fromthe cylinder head 33 toward the cylinder block 32. In other words, awire outlet joint end 4 a of the oil control valve 4 faces toward thecylinder head 33. Similarly, the high lift driving member 3372 of theintake valve driving member 337 is arranged close to the oil controlvalve 4. In other words, the high lift driving member 3372 of the intakevalve driving member 337 is more close to the oil control valve 4 thanthe low lift driving member 3371.

The effectiveness of the present invention is that an oil control valveseat 339 is mounted to a surface on the intake port 331 side of thecylinder head 33 and located on an outer wall of the timing chainchamber 330, the oil control valve seat 339 is mounted between theintake port 331 and not exceeding the greatest height of the throttlevalve 6; the oil control valve 4 is mounted on the oil control valveseat 339 in such a way to face from the cylinder block 32 toward thecylinder head 33, namely a wire outlet joint end of the oil controlvalve 4 facing toward the cylinder block 32, whereby the oil controlvalve 4 is set away from high temperature of the engine 3 to prevent theoil control valve seat 339 from becoming a heat concentration object andto improve the durability of the oil control valve 4 and also to realizeeasy arrangement and eliminate interference of the oil control valve 4with the maintenance of other parts. Further, the high lift drivingmember 3372 of the valve driving member 337 is arranged close to the oilcontrol valve 4, namely, the high lift driving member 3372 of the valvedriving member 337 being more close to the oil control valve 4 than thelow lift driving member 3371, whereby the oil path that the oil controlvalve 4 supplies oil to the high lift driving member 3372 is shortenedand the pressure loss is reduced thereby making the high lift drivingmember 3372 operating in a more reliable manner. Since the oil path thatthe oil control valve 4 supplies oil to the high lift driving member3372 is shortened, the loss of oil pressure that the oil control valve 4supplies to the high lift driving member 3372 is reduced, so that theoil pump 311 that supplies the oil can be miniaturized to thereby reducethe installation cost of the oil pump 311 and the consumption of powerof the engine 3, and allows internal arrangement of the engine 3compact.

It will be understood that each of the elements described above, or twoor more together may also find a useful application in other types ofmethods differing from the type described above.

While certain novel features of this invention have been shown anddescribed and are pointed out in the annexed claim, it is not intendedto be limited to the details above, since it will be understood thatvarious omissions, modifications, substitutions and changes in the formsand details of the device illustrated and in its operation can be madeby those skilled in the art without departing in any way from the spiritof the present invention.

1. A variable valve lift mechanism for engine and arrangement of oil control valve, the engine comprising a cylinder block mounted on a crankcase and a cylinder head mounted on the cylinder block, the cylinder head forming, in one side, an intake port and an intake valve and an exhaust port and an exhaust valve on another side, a throttle valve communicating through an intake tube with the intake port, the intake valve and the exhaust valve being provided therebetween with a camshaft base, the camshaft base rotatably supporting a camshaft, the camshaft carrying therein an intake cam assembly and an exhaust cam assembly, the intake cam assembly and the exhaust cam assembly respectively driving an intake valve driving member and an exhaust valve driving member, wherein the intake cam assembly comprises a first intake cam and a second intake cam, the intake valve driving member comprising a low lift driving member corresponding to the first intake cam and a high lift driving member corresponding to the second intake cam, the low lift driving member and the high lift driving member forming therein a hydraulic cylinder, the hydraulic cylinder receiving therein hydraulically operable pistons, the oil control valve comprising a driving oil passage communicating the hydraulic cylinder, characterized in that the high lift driving member of the intake valve driving member is more close to the oil control valve than the low lift driving member and the driving oil passage of the oil control valve and the high lift driving member is shorter than the driving oil passage that the oil control valve drives the low lift driving member.
 2. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the surface of the cylinder head on the intake side is provided with an oil control valve seat, which is located on an outer wall of a timing chain chamber, the oil control valve seat being lower than a greatest height of the throttle valve, the oil control valve being mounted to the oil control valve seat.
 3. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 2, wherein the oil control valve seat forms an opening, which faces the cylinder block, whereby the oil control valve is mounted to the oil control valve seat in such a way to face from the cylinder block toward the cylinder head, the oil control valve having a wire outlet joint end facing the cylinder block.
 4. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 2, wherein the oil control valve seat forms an opening, which faces toward the cylinder head, whereby the oil control valve is mounted to the oil control valve seat in such a way to face from the cylinder head toward the cylinder block, the oil control valve having a wire outlet joint end facing toward the cylinder head.
 5. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the cylinder block comprises a timing chain tensioner arranged therein, the oil control valve seat being arranged to be substantially in line with the timing chain tensioner.
 6. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the oil control valve seat and the camshaft base are integrally formed with the cylinder head.
 7. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 3, wherein the oil control valve is mounted to the oil control valve seat and is substantially parallel to a wall of the cylinder head.
 8. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the driving oil passage comprises a first driving oil passageway and a second driving oil passageway corresponding to the hydraulic cylinder, the first driving oil passageway being associated with the low lift driving member, the second driving oil passageway being associated with the high lift driving member.
 9. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the first intake cam is a low lift valve intake cam, the second intake cam being a high lift valve intake cam.
 10. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the engine is arranged substantially horizontally, the oil control valve seat being substantially parallel to an intake tube, the oil control valve being arranged on the cylinder head of the engine in a substantially horizontal manner.
 11. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the primary oil supply passage has an end toward the crankcase, the end forming a crankshaft oil supply passage.
 12. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 11, wherein the crankshaft oil supply passage has an end provided with a throttle arrangement.
 13. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 1, wherein the primary oil supply passage has an end toward a cylinder head cover, the end being provided with a valve driving member oil supply passage.
 14. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 13, wherein the valve driving member oil supply passage is provided with a throttle arrangement.
 15. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 12, wherein the throttle arrangement comprises a nozzle.
 16. The variable valve lift mechanism for engine and arrangement of oil control valve according to claim 14, wherein the throttle arrangement comprises a nozzle. 